remote server

BIND is the Berkeley Internet Name Domain, DNS server. It is wildly used on UNIX and Linux like oses. You can use following tools to troubleshoot bind related problems under UNIX or Linux oses.

Task: Port 53 open and listing requests

By default BIND listen DNS queries on port 53. So make sure port 53 is open and listing user requests. by running any one of the following tests. See if you can telnet to port 53 from remote computer:$ telnet remote-server-ip 53 ORtelnet ns1.nixcraft.org domain Output:

Trying 192.168.0.5...
Connected to ns1.nixcraft.org.
Escape character is '^]'.

If you cannot connect make sure firewall is not blocking your requests. Next use netstat command to list open and listing port 53 on server itself:$ netstat -tulpn | grep :53 OR# netstat -atve Output:

Make sure iptables firewall is not blocking request on server:# iptables -L -n OR# iptables -L -n | less Make sure named is running:# /etc/init.d/named status If not start named:# chkconfig named on # service named start

Task: Use log files

You can use log files after starting/restarting bind to see error messages:# tail â€“f /var/log/message Output:

Plesse note that if named-checkconf did not find any errors it will not display in output on screen.

Check zone file syntax for errors. named-checkzone is zone file validity checking tool. named-checkzone checks the syntax and integrity of a zone file. It performs the same checks as named does when loading a zone. This makes named checkzone useful for checking zone files before configuring them into a name server.# named-checkzone localhost /var/named/localhost.zone OR#named-checkzone nixcraft.org /var/named/nixcraft.org.zone Output:

zone nixcraft.org/IN: loaded serial 12
OK

Task: Testing BIND/DNS with utilities

You can use host and dig utilties to test your bind configuration.

host: host is a simple utility for performing DNS lookups. It is normally used to convert names to IP addresses and vice versa.

dig: dig (domain information groper) is a flexible tool for interrogating DNS name servers. It performs DNS lookups and displays the answers that are returned from the name server(s) that were queried. Most DNS administrators use dig to troubleshoot DNS problems because of its flexibility, ease of use and clarity of output. Other lookup tools tend to have less functionality than dig.